Jeff Probst on Survivor 27: Expect Betrayals: "It's Inevitable!"

For 26 seasons, legions of fan favorite castaways have outwitted, outplayed and outlasted each other in a quest for CBS' $1 million Survivor prize, but when the series heads to the Philippines Sept. 18, 10 of those former players will have to go against their very own loved ones.

In the mix for season 27's Blood vs. Water installment are previous champs Aras Baskauskas (playing against brother Vytas), Australia winner Tina Wesson (against daughter Katie Collins) and one of Survivor's inaugural players, Gervase Peterson, who will face off against his niece, Marissa Peterson.

As Survivor's host Jeff Probst explains, blood may not necessarily be thicker than water as the castaways' 39 days of competition wage on. "This season will definitely have families and couples talking about their own relationships. It's inevitable," he tells Us Weekly ahead of Blood vs. Water's Sept. 18 premiere. "You can't help but wonder: What would you do?"

One of the more controversial returnees this season is none other than Colton Cumbie, the polarizing Survivor: One World contestant who was medically evacuated due to illness on day 16 of his 2012 season. The outspoken Cumbie will try to outlast his fiance, Caleb Bankston, who, as Probst hints, may have an advantage over the second-time player.

"Bringing back Colton was definitely a controversial decision. But aren't you just a little curious about his fiance? I mean, who chooses Colton as a partner?" reasons Probst to Us. "Caleb is super likable. Makes no sense."